The estimate of lifespan for ideal incompressible MHD systems

This paper concerns the lifespan estimate for three-dimensional ideal incompressible MHD systems. By introducing $L^{3/2}$-type energy, we lower the regularity assumption for the initial data as well as the order of the highest derivatives involved in the total weighted energy estimate. The new weights proposed in this paper are symmetric, unified, and compatible with both $L^2$-type energy and $L^{3/2}$-type energy.